Plunger type switch



Oct. 23, 1951 C. A. WOODCOCK ETAL PLUNGER TYPE SWITCH Filed Feb. 17.194? CHARL A. \Alooococn.

. SHERMAN E. Won/10K.

JOHN W. Hoses.

Patented Oct. 23, 1951 Charles 'A. Woodcock, Sherman E. Womack, and JohnW Hobbsspringfield -lll, assi gnog s to John W. Hobbs Qorporation,Springfield, 111., a corporation of Delaware application-Farmers 17,194v, sesame-129,176

J '3 Claims.

This invention relates to an electric switch and particularly to aplunger type switch characterized by the sturdiness "of itsconstruction, re-' liability of operation and outstanding ease ofmanufacture and assembly of its components.

"A large number of switch constructions have heretofore been proposedwherein the movement of a plunger member effects the opening "or closingof an electric circuit through the contact eleme'nts of the switch. Suchplunger type switches may be either of the normally open construction,wherein the circuit through the switch is normally open but closed bymanipulation of the plunger, or of the normally closed constructionwherein manipulation of the plunger effects the opening of the switchcontacts.

A feature of this invention is the provision of an extremely simple andreadily manufacturable plunger type switch construction which'may beconveniently assembled as either a normally open or a normally closedswitch and which utilizes substantially identical components for eithertype of switch.

A further feature of this invention is the :provision of a plunger typeswitch construction wherein the switch terminals include hollow membersspecially constructed to receive and releasably retain wire end terminalmembers inserted therein in good conducting relation. By thisconstruction, the problem of securing proper electrical connection ofthe switch in a part-icu lar wiring system is completely eliminated,particularly in the utilization-of the switch in automotive wiringsystems. Furthermore, 'in the switch construction embodying thisinvention, the wire end terminal members are completely en'- closedwithin the insulating body of the switch and hence there is nopossibility of such terminal members being inadvertently shorted by ac=c-ldental contact of the switch with an adjacent conducting member.

Accordingly, it is an object of this invention to provide an improvedelectric switch of the :plunger operated type.

Another object of this invention is to provide an improved plunger typeelectric switch char= acterized by outstanding ease of manufaeture andassembly of its components.

A further object of this invention is to provide an improved plungerswitch construction wherein substantially identical components may beutilized to effect an assembly of the switch as either a normally openconstruction or a normally closed construction.

;A particular object of this invention is to :provide an improvedplunger switch construction particularly adaptable for use in wiring"systems employing terminal members on the wire ends to effectelectrical connection of the switch unit in the system. A switchconstructed in accordance with this invention will releasably retainsuch'wire end terminal members "in good electrical connection with thecontact elements "of the switch and furthermore, will eliminate therpos= sibilitynf accidental shorting connections occur-*- ring-acrossthe terminal members.

The specific nature of thisinvention as Well as other objects andadvantages thereof will *be= come apparent to those skilled in the artfrom the following detailed description of the annexed sheet of drawingswhich, by way of preferred ex ample only, illustrate two specificembodiments of the invention.

"On the drawings:

#F-i'gure l is a side-elevational view of a switch unit embodying thisinvention;

Figure 2 is an end elevational view of the switch Figure 1.';

Figure 3 is a longitudinal sectional view taken along the plane ill-IIIof Figure '2, and illus traiting the interior "switch construction for anormally closed type of plunger switch;

' Figure *4 is a transverse sectional view taken on 'the plane IV -IV'of'Fi'gure 3.;

Figure 5 is a view similar to Figure 3 but showing the interior switchconstruction an a normally open type of plunger switch.

{As shown on the "drawings:

Referring to Figures -1 lllflfillghk. switch element embodying thisinvention is shown "as- 35 seiamen it-hi clfp-shapedcas'ihg' lflwhichmay suitably dimensioned to perm-it such unit to be snugly insertedii-'1 the 'cjasin 1-0 through the la? e open 'ehdthereof. Block unit l-2 is p'refer amyencmea from any one of sve r' al well known electricalinsulating "rials and is most con ve'nien-tly formed as assembly of twoidentical. half po F261 a d 12b, respectively, which are ifoinablea-long a -di'aintral plane as best'shown in Fig. 2.

insulating block nnit 12 mg be conveninnyretained within casing ID bythe provision c: s. spluralitybf integral tabs We 'on the open end ofthe casing =|=ll which are bent inwardly afterthe insertion ofinsulating block 12. Suit-- able recesses We are provided :in theadjacent end face of insulating block I2 to receive the ina 3 wardlyprojecting portions of the tabs I, and hence maintain the end face ofthe switch unit of substantially flush construction.

The half portions I2a and I211 of the insulating block I2, whenassembled, define a large cylindrical cavity I4 which is substantiallycoaxial with the axis of the block unit I2 and which has a reduceddiameter opening I6 communicating with the inserted end face of theblock unit I2.

Opening I6 thus communicates with the central.

aperture It!) provided in the base portion Illa of the casing I0. In theother axial end of the block unit I2 I ing I6 in the insulating blockI2.

"switching action comprises a disk-like annular there are defined aplurality of recesses I8 which open in the adjacent end face of theinsulating block I2. In the illustrated construction, two such recessesI8 are provided and such recesses may conveniently be of cylindricalconstruction. The recesses I8 are respectively in communication with thecavity I4 by the provision of passages extending longitudinally from theend of each of the recesses l8 generally parallel to the axis of theinsulating block unit and communicating with cavity I4 through twoaxially spaced, generally radial passages 22 and 24 respectively.

A metallic terminal member 26 is mounted in each of the recesses I8.Such terminal members comprise generally cylindrical body portions 28awhich are longitudinally split as indicated at 2519 (Figure 2) and arepreferably normally expanded to a, slightly greater diameter than thatof the recesses 26 so that a slight resilient compression of such splitbody portion is required to efiect the assembly thereof in recesses 26.This arrangement insures that the terminal members 28 will be snuglyretained within the recesses I8.

Each of the terminal members 26 is provided with an integral axiallyextending arm 260 which, when the terminal member is assembled intoblock unit I2, lies snugly in the respective longitudinally extendingpassage 20. The end of such arm portion 260 is bent generally radiallyinwardly as indicated at 26d, and projects through the radial passage 24into the interior of cavity I4. Since each of the terminal members 26 isidentical, the end portions 26d are thus arranged within cavity I4 inspaced opposed relationship.

The recess defined by the hollow portion 26a of the terminal members 26is suitably dimensioned so as to permit the snug insertion therein of aconventional terminal member 28 which is secured in customary manner tothe bare ends of an insulated wire 30. To resiliently retain theterminal members 28 in an inserted position, the walls of hollow portion26a are deformed inwardly at one or more points to provide an inwardlyprojecting spring tongue 26c. 26c therefore snap into engagement withan' annular groove 28a which is conventionally provided on the wire endof the terminal members 28. It will be noted that in their insertedposition, the metallic portions of the wire end terminals 28 arecompletely enclosed within the insulating body I2. Hence, allpossibility of such end terminal members being accidentally shorted by aconducting member adjacent to the switch is substantially eliminated.

To effect a selective electrical connection of :1

the end portions 28d of the terminal members 26, a disklike conductingmember 32 is provided which is movable within the cavity I4 by anoperating plunger 34. Operating plunger 34 may be Tongues piece 32a ofsuitable electrically insulated material which is secured in an annulargroove 34b provided on the inserted end of operating rod 34 by thesimple expedient of peening over such end. Around the periphery of diskbase 320. an annular conducting rim 32b is mounted. Rim 32b ispreferably substantially U-shape in cross section and is permanentlyassembled on disk base 32a by a bending operation. The end face ofconducting rim 321) will, therefore, effect an electrical connectionbetween end portions 26d of the terminal members 26 when the operatingrod 34 is moved outwardly to its extreme position with respect to' thecavity l4.

A spring 3'! is provided which is insertable in the recess 34a ofoperating rod 34 and operates between operating rod 34 and end wall I4aof the cavity I4. Preferably, a spring guide member 38 is providedhaving an enlarged head portion 38a seated in a suitable recess I4b inwall Ida of the cavity I4, and a stem portion 38b insertable within thespring 31 and hence, also, within the recess 34a of operating rod 34.Therefore, when operating rod 34 is pushed inwardly against the bias ofspring 37, the spring guide 38 cooperates with rod 34 in telescopicrelation.

From the foregoing description it is believed that the operation of theplunger type switch disclosed in Figures 1 through 4 is completelyobvious. Such switch normaliy effects electrical connection betweenterminal members 26 by vir-' tue of the conducting ring element 32 beingheld tightly in engagement with the terminal end portions 2611, underthe outward bias exerted by the spring 31. When the operating rod orplunger 34 is moved inwardly with respect to the cavity I4, theelectrical connection between the termiine'nts are employed as in thenormally closed modifications of Figures 1 through 4. A casing Ifl,insulating block unit I2, mounting bushing 33, operating plunger 34,conducting ring 32, and spring guide 38 are identical to similarlyidentified elements of the modification of Figures 1 to 4.-

The terminal elements 42 which are employed in the modification ofFigure 5 have identically shaped hollow cylindrical body portions 42a.The

arm portions 420, however, are of shorter length than the arm portions260 of the terminals 25' p and the inturned ends 42d of such arms 42cproconveniently journaled for sliding movement by l the provision of anannular mounting bushing 36 ject into the interior of cavity I4 throughradial passages 22. The conducting ring unit 32 is not rigidly securedto operating plunger 34 but is operatively connected to the plunger 34by virtue of being positioned on spring guide 38 between main spring 37and an auxiliary spring 44. Main spring 3'! is somewhat heavier thanauxiliary spring as, and the characteristics of such springs areselected so that, in normal position, the conducting ring 32 isfloatingly positioned in the cavity id in a position outwardly from, andout of contact with, the end portions 42d of the terminals 42. Inwardmovements of operating plunger 34, however, will effect an inwardmovement of conducting ring 32 to engage the metallic rim portion 32bwith the contact ends 4211 of the terminal members 3 2. It is thereforeapparent that the switch unit shown in Figure 5 will operate as anormally open type plunger switch.

Both types of switch units herein described are of identical exteriorconfiguration, and hence may be readily substituted in any particularelectrical circuit where space requirements are limited. Furthermore,the provision of threads on the exterior of the mounting bushing 535permits the switch unit to be conveniently mounted on a panel, wall orsimilar surface.

It is also apparent that all of the major components of a switchconstruction embodying this invention may be economically manufacturedby high production, low cost operations, such as molding and stamping,and a minimum of machining is required. Furthermore, the fact thatsubstantially identical components are employed to assemble two distincttypes of switches obviously effects an additional substantial saving inmanufacturing costs.

It will, of course, be understood that various details of constructionmay be varied through a wide range without departing from the principlesof this invention and it is, therefore, not the purpose to limit thepatent granted hereon other- 1 wise than necessitated by the scope ofthe appended caims.

We claim as our invention:

1. A plunger type switch comprising a generally cylindrical insulatingbody having an interior cavity formed therein and extending therealongfor a portion of the length thereof and opening to one face of saidbody, and a plurality of parallel axially extending recesses opening tothe opposite face of said body and communicating with said cavitythrough an interior wall of said body, a metallic terminal member havinga hollow cylindrical body portion disposed in each of said recesses,said terminal members each having an axiall extending arm portionextending through said interior wall of said body into said cavity, theintermediate portions of said arm portions being entirely encased bysaid insulating body and extending along said body inwardly of the wallof said cavity and having inwardly extending terminal end portionsextending within said cavity and forming contacts for the switch, aplunger axially reciprocable in said cavity, a conducting disk disposedin said cavity operably connected with said plunger and movable to andfrom engaging connection with said terminal end portions of said axiallyextending arm portions, and resilient means urging said plunger tooutward position with respect to said cavity.

2. A plunger type switch comprising an insulating body having aninterior cavity having an inne end wall and extending along said bodyfrom said end wall and opening to one end face of said body, a pluralityof recesses in said body on the opposite side of said inner end wallfrom said cavity and opening to the opposite end face of said body fromsaid cavity, metallic terminal members having body portions disposed insaid recesses, and integral contact arms extending from said recessesthrough said inner end wall of said insulating body into and along saidcavity and having terminal end portions extending radially within saidcavity, said wall completel encasing the intermediate portions of saidarm per-- tions, an operating rod axially reciprocable in said cavityand having an end portion projecting out through said opening of saidcavity, a rodlike guide member disposed in said cavity in 00- axialalignment with said operating rod, a contact disk on said guide memberhaving a conducting rim portion engageable with said terminal end'portions of said arms to complete a circuit thereacross, a plungecarried by said operating rod for reciprocating said contact disk onsaid guide member, and resilient means urging said plunger away fromsaid disk. 7

3. A plunger type switch comprising a generally cylindrical insulatingbody formed of two identical half portions joinable on a diametralplane, a casing surrounding said body and securing said half portions inassembled relation with respect to each other, said insulating bodyhaving an inner wall defining an interior cavity opening in one face ofthe body and terminating in an end wall interiorly of the body, and aplurality of parallel spaced axially extending recesses separated fromsaid cavity by said end wall and opening to the opposite end face ofsaid body, registering axially extending slots formed in the abuttingfaces of said half portions and forming passageways from said recessesto said cavity, metallic terminal members having hollow cylindrical bodyportions disposed in said recesses and having integral axially extendinarm portions extending through said passageways formed by saidregistering slots and along said cavity, said hollow body portionsdetachably receiving wire end terminals inserted therein, said armportions each having radially inwardl extending end contact portionsdisposed in said cavity in spaced opposed relationship, a plungeraxially reciprocable in said cavity, a conducting disk disposed in saidcavity and operably connected to said plunger and movable thereby intobridging relation across said end portions, and resilient means urgingsaid plunger outwardly with respect to said cavity.

CHARLES A. WOODCOCK. SHERMAN E". WOMACK. JOHN W. HOBBS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 676,280 Schulz June 11, 1901'.741,905 Ham Oct. 20, 1903 1,114,813 Shreve Oct. 27, 1914- 1,699,601Appleton Jan. 22, 1929 2,166,803 De Reamer July 18, 1939 2,224,551Roeder Dec. 10, 1940 2,375,891 Bolley May 15, 1945- 2,413,148 MartinDec. 24, 1946 2,473,252 I-Iutt June 14, 1949 FOREIGN PATENTS NumberCountry Date 337,508 Germany June 2, 1921

